The present invention relates generally to a belt let-off or unwind device for unwinding fabrics or material from a roll. Material rolls can be extremely heavy, weighing over 2000 pounds, and it is necessary to unwind the fabric from these rolls for further use of the fabric. The rolls of material are often not uniform and a problem exists in unwinding the rolls to a take-up unit without causing wrinkles, puckers or creases, and providing the material to the take-up roll in as good a condition as possible. Problems are caused when the material roll is not driven smoothly in addition to when the rolls bounce in the unwind apparatus during unwinding. It is also important to maintain lateral alignment of the rolls without interfering with the operation of the unwinding device. In addition, because of the size and weight of the material rolls, it is difficult to load and unload the rolls from the let-off unit.
It is known in the prior art to provide a device for unwinding various types of rolls. For example, U.S. Pat. No. 4,757,951, issued to Ludszeweit, discloses one such device. The apparatus disclosed in Ludszeweit is for changing bobbins of wrapping material in a cigarette making machine. Ludszeweit provides for the continuous feeding of rolls into the unwinding portion of a machine and for unwinding the rolls thereat. Other unwinding devices for various materials are disclosed in U.S. Pat. No. 2,977,058, U.S. Pat. No. 4,093,139, U.S. Pat. No. 3,643,885 and U.S. Pat. No. 2,345,656.
Thus, various means for unwinding rolls are known. However, functional shortcomings of the prior art devices that this invention attempts to solve are numerous. Heavy rolls of material are difficult to load and it is difficult to drive them smoothly and continuously to provide the good unwind characteristics, particularly as the roll unwinds and becomes smaller in diameter. In addition, irregularly shaped rolls are particularly inclined to become misaligned in an unwind device.